Lawmakers are working against an Oct. 17 deadline for raising the nation's borrowing limit.
Mikulski, the Senate Appropriations Committee Chairwoman, urged her colleagues to support a measure from Senate Majority Leader Harry Reid (D-Nev.) that would raise the debt ceiling by nearly $1 trillion. A procedural vote to advance that legislation is scheduled for Saturday.
It's unclear whether Reid will have the votes. The measure would raise the debt ceiling but would not cut spending, and it could be difficult for Republicans to back a "clean" debt ceiling hike.
"If we as a nation are going to incur more debt, then we need to find real savings," Sen. John Barrasso (R-Wyo.) said Thursday. "It’s time to set [spending] priorities."
The House is expected to pass its own short-term debt-ceiling extension, possibly later this week, but many Republicans are trying to add language that would cut entitlement programs, including ObamaCare.